Why hydrogen rather than electric?

Electric cars are often touted as the answer to a greener motoring future. It's true that their overall emissions are usually much lower than those from a conventional petrol or diesel car particularly if the electricity is generated from renewable sources.

However, there is one key problem with battery-powered cars: range. The distance you can travel on a single charge is seriously limited, and when you do run out of juice it takes several hours to recharge the batteries.

'For ranges of over 150 miles, I don't believe there's a technology on the horizon that can be remotely as efficient as fuel cells,' said Spowers.

'There will certainly be battery electric vehicles in urban use it won't just be hydrogen fuel cells but I don't think driving from London to Edinburgh on batteries makes much sense.'